Gas treatment apparatus and method

ABSTRACT

A treatment plant for polluted air or gas includes a water tank having a vertical inlet conduit communicating with the upper end of the tank. The tank is divided into upper and lower water chambers by a transverse filter assembly. In the inlet conduit, the gas is wetted from a spray nozzle and then directed through filtering elements to remove solid particles prior to being discharged into a lower chamber of the water tank. The gas is further purified in passing through the water, in the lower and upper water chambers, and through the filter submerged assembly. The gas to be treated may be received from building enclosures, or may be received from intake stacks collecting polluted air from particularly contaminated outside areas such as city streets.

9 l.. United States aient t191 t1 u 3,733,72

Hatchel [451 May 22, 1973 [54] GAS TREATMENT APPARATUS AND 537,5094/1895 wardle et al. ..261/118 UX METHOD 1,423,696 7/1922 Stevens..55/90 [76] Inventor: Charles Lee Hatchel, Rte. 12, Box PrimaryExaminer Frank w Lutter 6MM Fort worth Tex 76112 AssistantExaminer-Vincent Gifford [22] Filed May 11, 1971 Attorney-Cecil L. Woodand Peter J. Murphy [21] Appl. No.. 142,217 [57] ABSTRACT [52] U.s. ci.ss/9s, 55/90, 55/98, A treatment Plat fer Pellllled ai' ef gee-inellldes e 55/217, 55/227, 55/233 55/25655/318 Water tank having aVertical inlet COndUt Commu- 5 5 /517 261/DIG- 9 nicating with the upperend of the tank. The tank is di- [5 i] Int. Cl. Bold 47/02 vided inteUpper and lower water Chambers by a trans- [58] Field ofsearch ..55/97,98, 220, 223, verse filter assemblyln the inlet Conduit, the gas iS55/224, 227-229, 233-234, 244, 255, 2561 wetted from a spray nozzle andthen directed through 315, 31g, 476, 512, 515 51g, 90,95; 261/76,filtering elements to remove solid particles prior to 78 A, 118, DIG. 9,DIG, 75 being discharged into a lower chamber of the water tank. The gasis further purified in passing through the [56] References Cited water,in the lower and upper water chambers, and through the filter submergedassembly. The gas to be UNITED STATES PATENTS treated may be receivedfrom building enclosures, or 2,332,063 10/1943 Davis .Q ..55/256 X maybe received from intake Stacks Collecting polluted 2,721,065 10/1955Ingram... ...5S/244 UX air from particularly contaminated outside areassuch 3,142,548 7/1964 Krantz ..55/233 X as city streets. 3,353,33611/1967 Caballero ..55/244 X 3,664,094 5/1972 Barkovitz ..55/223 7Claims, 15 Drawing Figures PATENTEL HY 2 2 {Q SHEET l F 5 INVENTORCharles Lee Hofchel f/Qz 250V/22M ATTORNEY PATENTEL :im 2 m3 SHEET E F 5THERMOSTAT 'TRANSA FORMER HEATmG ELEMENT HunMDHY ACTUAYED MOTOR CONTROLREVERSIBLE MOYOR 'www Fig'g INVENTOR. Charles Lee Hofchel ATTORNEYPATENT@ w 2 2 m5 SHEET 3 F 5 f8 hw @Y i INVENTOR. Charles I ee Hoi'chelATTORNEY PATENTEL m22 m5 3, 733 782 snm u 0F 5 INVENTOR. Charles LeeHo'fchel BY @J www ATTORNEY PATENTEWMSH 3; 733,782

SHEET S F 5 lll - l, l/l

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im [[3 FIREPLCE /H RANGE /V "00 INVENTOR. HF; horles Lee Hochel F lg. l5C ELEC. BY POWER SUPPLY ATTORNE Y GAS TREATMENT APPARATUS AND METHODBACKGROUND AND SUMMARY OF THE INVENTION This invention relates to thetreatment and purification of polluted air or other gases.

The increasing pollution of air caused from contaminants introduced intothe air by increasing human and industrial activity is creating numeroushealth and other hazards. One of the known existing hazards is that ofsmog, which is largely derived from hydrocarbons and from their reactionwith oxides of nitrogen in the sunlight; and its threat to health isbecoming in creasingly apparent.

Because of the increasing awareness of air pollution, studies are beingmade to determine its effects and additional hazards are beingdiscovered as a result of these studies. There is increased concern inregard to measures which may be taken to decrease or even prevent airpollution. There is a growing belief that, particularly in large cities,it may be necessary to go so far as to place decontamination units inthe streets to overcome certain of the disadvantages of increased humanactivity.

An object of this invention is to provide an apparatus, method, andsystem for treating of polluted effluent air or gases from buildingenclosures, and for collecting and treating polluted air from an outdoorcontaminated area.

Another object of this invention is to provide an effective apparatus,method, and system for treating polluted air such as smog.

A preferred form of apparatus for accomplishing these objects includes acollection conduit with forced air means for flowing the polluted airinto the treatment apparatus. The air is first wetted and passed throughfiltering devices to remove heavier particles from the air, then the airis passed through a body of water including a submerged filteringelement to further purify the air prior to its discharge.

The novel features and the advantages of the invention, as well asadditional objects thereof, will be understood more fully from thefollowing description when read in connection with the accompanyingdrawings.

DRAWINGS FIG. l is a diagrammatic view of a system for collectingpolluted air from the atmosphere and processing the air in a treatmentplant;

FIG. 2 is a diagrammatic sectional view through a tower, as shown inFIG. l, for collecting air from the atmosphere;

FIGS. 3 through 6 are sectional views taken in the indicated planes inFIG. 2 illustrating details of the operating components at the top ofthe tower;

FIG. 7 is a sectional view taken in the plane 7-7 of FIG. 2 illustratingthe underground collection conduits;

FIG. 8 is a sectional view in a vertical plane illustrating a differentoperative condition of components at the top of the tower as seen inFIG. 2;

FIG. 9 is a schematic circuit diagram for controlling apparatuscomponents in the tower;

FIG. l is a diagrammatic view of the air treatment plant illustrated inFIG. l0;

FIG. ll is a fragmentary detail view taken along the line ll-ll of FIG.10;

FIG. 12 is a diagrammatic view of an air treatment plant associated witha building structure or enclosure, of intermediate size, such as arestaurant, retail store, small business or other operation;

FIG. 13 is a diagrammatic view of an air treatment plant similar to thatof FIG. l0, with the addition of a bypass filter;

FIG. 14 is a diagrammatic view of an air treatment plant associated witha larger facility such as a factory, which includes a conventional tallstack for draft purposes; and

FIG. 15 is a schematic circuit diagram for operation of an air treatmentsystem, including a treatment plant as indicated in FIG. 10, in aresidence.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description,reference will be made to several systems which include an air treatmentplant for the treatment of atmospheric polluted air or for the treatmentof air or other gases which are accumulated in enclosures such asbuildings ranging from large industrial factories to small residences.

FIGS. 1 through 1l of the drawing are concerned with an overall systemfor the circulation and treatment of atmospheric air; and the remainingFIGS. 12 through 15 are concerned with systems associated with buildingsor other enclosures to treat the air discharged from such enclosures.

Referring particularly to FIG. 1, a system for the treatment ofatmospheric air includes inlet towers 10 which would be placed instrategic locations, along city streets for example, in accordance withthe volume of air required to be treated. The towers are provided withinlet openings at the top including suitable screens 11 for preventingthe ingress of birds and blowing debris for example. The towers aremounted on suitable supports and communicate, at the bottoms thereof,with an underground tunnel or conduit l2 for conducting the treated airto the treatment plant 16. Where a number of inlet towers 10 arecommunicated with a common main conduit 12, these will be connected tothe main conduit through suitable lateral conduits 13.

Each of the towers may be provided with an individual blower, as will bedescribed, for drawing air into the tower inlet and for forcing the airthrough the main conduits to the treatment plant. An additional largeblower 14 may be provided in the main conduit 12 at the inlet side ofthe treatment plant 16, to provide forced flow of the air through thetreatment plant, for treatment as will be described.

The treated air may be returned to the atmosphere at the treatment plantthrough a suitable discharge stack, or it may be desirable or necessarythat the treated air be discharged to a discharge conduit system 17,which possibly may be also underground, for discharge to the atmosphereat a location remote from the treatment plant.

FIG. 2 and 8 illustrate, in vertical section, an inlet tower l0 as seenin FIG. l. Referring to the drawings, the tower preferably comprises ahollow structure including cylindrical walls 20, fabricated of metal orany other suitable material, and being mounted on a suitable concretebase 21. As seen in FIG. 2, the tower may be positioned adjacent a citystreet indicated by the concrete curb structure 22. At the base of thetower a conduit 23 carries the inlet air through the concrete base tocommunicate with the lateral conduit 13.

At the upper end of the tower, the inlet screen 11 preferably defines anupward extension of the cylindrical tower wall to provide an inletopening around the entire periphery of the tower. A cap 24 is supportedabove the inlet screen 11 encloses the top of the tower.

The tower is provided with a blower, shown in the form of a fan 27driven by an electric motor 28, positioned immediately below the towerinlet opening defined by the screen 11. In the illustrated form, the fanblades have a span substantially corresponding to the inner diameter ofthe tower structure for withdrawing air through the inlet opening andforcing the air downward through the tower structure to the main conduit12. Obviously, other forms of forced air blowers may be provided.

To prevent the drawing into the tower of moisture in the form of rain orsnow, and to protect the blower from these elements, means are providedfor closing l the tower inlet in the event of such inclement weather andfor stopping operation of the blower. As best seen in FIGS. 2 and 8, aninwardly directed peripheral flange is provided on the tower wall 20adjacent to the base of the screen l l; and this flange defines a seatfor a closure plate 30 which is seen as a disc-like member as viewedfrom the bottom in FIG. 5. The closure plate is normally stored withinthe tower cap 24, and is guided for vertical movement between its storedposition, illustrated in FIG. 2 to its closed position, illustrated inFIG. 8, on four vertical guide rods 31 suitably anchored to the towerstructure. The plate 30 is supported and moved vertically by means of ahoist drum 32 and associated cable 33, the hoist drum being driven by as uitable electric motor 34.

An automatic control system is provided for controlling the operation ofthe closure plate 30, and the associated operation of the fan motor 28,which is responsive to atmospheric humidity conditions or moisture. Asbest seen in the schematic circuit diagram of FIG. 9, and additionallyin FIGS. 2 and 8, the control system includes a motor control 37contained in a suitable housing mounted on the top of the tower cap 24,for controlling the operation of the closing plate motor 34 and theblower motor 28. The blower motor 28 will normally be energized throughother controls when the system is in operation.

The motor control 37 includes a control device which is responsive toeither a measurement of atmospheric humidity or a measurement ofaccumulated moisture resulting from precipitation. When the controldevice detects precipitation, the control 37 is actuated to shut off thefan motor 28 and to energize the hoist motor 34 to drive the hoist drum32 to lower the closure plate 30 on the guide rods 31. When the closureplate becomes seated on the flange seat 29, a limit switch 38appropriately mounted on the tower structure to be engaged by theclosure plate 30, actuates the motor control 37 to shut off the hoistmotor 34. The tower inlet is then closed to prevent ingress ofprecipitation such as rain, snow or sleet.

Apart from the purpose of closing the tower structure to prevent damageto tower components, and to lprevent accumulation of moisture within theconduits 12 and 13, the necessity for purification of the atmosphericair may be diminished during periods of precipitation, since theprecipitation will have a self-cleaning effect of the atmospheric air.

The motor control 37 also responds to the cessation of precipitationthrough humidity or moisture accumulation control, to again open thetower inlet and restart the blower 27. For this function, the motorcontrol 37 will respond by starting the hoist motor 34 to raise theclosure plate 30 to the stored condition of FIG. 2. When the platereaches the stored position, a second limit switch 39 is engaged andactuated by the closure plate, actuating the motor control 37 to shutoff the hoist motor 34 and to simultaneously start the blower motor 28.In this manner, each inlet tower 10 is controll'ed to automaticallyrespond to precipitation conditions.

An additional safety control is provided to assure 0peration of thetower controls in the event of freezing weather. For this purpose, theclosure plate 30 is provided with a heating element 41 which may be inthe form of an annular electric resistance coil mounted on the top ofthe closure plate. The heating element is connected to a suitable powersource through an expansible cable 42, connected between the closureplate and a transformer 43 mounted within the tower cap 24. Athermostatically controlled power controller 44, mounted on the top ofthe cap 24, controls the switching of electrical power to the heatingelement in response to the ambient temperature. Preferably, when thetemperature decreases to a point approaching freezing, the heatingelement 41 is energized to prevent the formation of ice on the closureplate until such time as the ambient temperature rises above the dangerpoint.

Referring to FIG. 10, which illustrates diagrammatically a preferredform of treatment plant 16 according to the invention, the air isdirected from the blower 14 to the inlet conduit 47 of the treatmentplant through an inlet section 48 of the main conduit l2 which extendsbetween the blower 14 and the plant inlet conduit 47.

The main conduit 12 includes a bypass section 49 which extends from theplant inlet conduit 47 and includes a vertical portion which connects atits lower end with the discharge conduit 17. A hinged diversion plate 50normally directs the gas from the inlet section 48 into the plant inletconduit 47, and alternatively into the bypass conduit 49.

The treatment plant 16 includes a closed water tank or vessel 51 and awater pump S2 for circulating water through the tank, both mounted on asuitable concrete slab 53. Since the tank and pump may be normallymounted outside of a building enclosure, the tank and pump are providedwith respective insulating enclosures 54 and 5S to insulate these unitsfrom the elements, with the tank insulating enclosure S4 extendingupward to include a portion of the inlet conduit 47 to which water issupplied as will be described.

In the preferred form illustrated in FIG. 10, the inlet conduit 47extends vertically upward from the upper wall of the tank 51 forconnection with an elevated inlet section 48 of the conduit 12; and theinlet conduit extends downward within the tank as will now be described.The tank is supplied with water from a water supply pipe S6; and thewater in the tank is maintained at a predetermined level through a floatvalve assembly 57, positioned within an inner screening enclosure 58 toprevent a debris from interfering with the float valve operation. Themaintained water level in the tank defines a tank gas chamber 60 abovethe water level in the tank, communicating with a discharge stack 61mounted on an extending vertically upward from the tank top wall todischarge air back to the atmosphere.

An access door 62 is provided in the tank wall for servicing thefloatvalve assembly -57`wh'en this becomes necessary.

A filter unit 65 is an annular disc-like assembly defining a horizontalpartition spaced from the bottom of the tank to define separate upperand lower water chambers 66 and 67 respectively within the tank areabelow the water level defined by the float valve assembly 57. The tankinlet conduit 47 extends downward within the tank to a point below thefilter unit 65; and the filter unit is annular in configurationextending between and being connected to the cylindrical tank walls andthe exterior walls of the inlet conduit.

The filter unit 65 is fabricated of upper and lower perforated plates 68of metal or other suitable rigid material, which enclose a body ofsuitable filter material 69 such as a fibrous, shredded or granularmaterial.

Ari inlet filter assembly 71 is mounted within the inlet conduit 47 andincludes a central perforated pipe 72 having an upper conical perforatedflange 73 which has a peripheral diameter corresponding to the innerdiameter of the conduit 47. A coupling 74, secured to the bottom of theperforated pipe 72, supports an annular perforated plate 75 extendingbetween the pipe and the inlet conduit walls. An annular elongatedfilter body 76 fills the annular space defined between the perforatedpipe and the conduit walls between the upper flange 73 and theperforated plate 75; this filter body being formed of a suitable filtermaterial such as spun glass, shredded metal, or granular material. Asolid pipe 77 is attached at its upper end to the coupling 74 to definea downward extension of the perforated pipe 72 which terminates in thelower water chamber 67 of the tank, preferably extending below the lowerend of the inlet conduit 47.

A water spray nozzle 79 is disposed in the inlet conduit 47 above theinlet filter 71. Water is supplied to the spray nozzle 79 from the pump52 through a supply pipe 80; and the suction pipe 81 for the pump 52ex'- tends through the tank wall into the lower water chamber 67 of thetank, the inlet end of the suction pipe being enclosed with a suitablescreen. The pump supply and suction pipes 80 and 81 may be covered witha suitable insulating layer to protect against freeze-up of these wate.rpipes.

It will now be seen that the air or gas entering the treatment plant 16flows first through the inlet filter assembly 71, then passes into thelower water chamber 67, upward through the filter unit 65, through theupper water chambers 66, then into the gas chamber 60 to be dischargedthrough the stack 61. During operation of the unit, the pump 52 isoperated to continuously discharge a spray of water from the spraynozzle 79. The incoming gas is first contacted by the water spray whichwets the larger solid particles within the air or gas and these areflushed down the central perforated pipe 72 and the solid pipe 77 to thelower water chamber 67. While the water circulates within the tank, theheavier particles will settle to the bottom of the tank to be collectedas sediment.

The perforated pipe 72 may be dimensioned so that its volume issubstantially filled by the water f'lowing -v lower end of the inletfilter assembly 71 the gas within the filter body passes through theperforated plate 75 and is then discharged downward in the annular spacebetween the solid pipe 77 and the inlet conduit 47 to be discharged intothe liquid within the lower chamber 67. In passing through the water inthe water chambers 67 and 66, and through the filter unit 65 the gas isfur ther filtered, and water soluble components removed before emergingto the gas chamber 60 for discharge -through the stack 61.

A screened sump 84 is connected with a discharge pipe 85 through asuitable service valve 86 for periodic flushing of the bottom of thetank to remove collected sediment from the tank, or for draining thetank for servicing and changing of filters as required for normalmaintenance.

FIG. l2 is a diagrammatic view of a system including a treatment plant16 as above described for treating the air exhausted from a structure ofintermediate size such as a retail store or restaurant 90 for example.FIG. 13 is an enlarged diagrammatic view of the treatment plant andassociated conduits and components. As best seen in FIG. 13, a blower 91is mounted on the roof of the building structure 90 and has its inletconnected to ari exhaust manifold 92 of the building ventilation system,for example. The blower outlet drives the exhaust air through the inletsection 48 of the main conduit to either the inlet conduit 47 of thetreatment plant or the bypass conduit 49. The treatment plant 16 asillustrated in FIGS. 12 and 13 is identical in structure and operationto that described in connection with FIG. 10.

An additional feature of the system illustrated in FIG. 13 is theprovision of a filter assembly in the bypass conduit 49 which serves thefunction of providing some filtering of the air or gas should it benecessary to bypass the treatment tank 51 and discharge the gas into anexhaust conduit system 17 such as an existing sewer I system.

The filter assembly 95 is similar in structure to the inlet filter 7 l,as particularly illustrated in FIG. 10, and includes an elongatedcentral perforated pipe 96 having la funnel shaped perforated flange 97at its upper end having an upper peripheral dimension corresponding tothe inner diameter of the bypass conduit 49. An annular perforated plate98, secured to the lower end of the pipe 96, fills the space between thepipe and the conduit walls; and the pipe, flange and plate define anelongated annular space which is filled with a suitable filteringmaterial 99. A spray nozzle 100 is disposed in the bypass conduit abovethe filter assembly 95; and is supplied from a water supply pipe 101through a service valve 102. When this filter system is employed, thewater is turned on to provide a spray which wets and collects theheavier solid particles within the air or gas, which are carried throughthe perforated pipe-with the water and are flushed into the sewer systemdefined by the discharge conduit 17. As in the filter assembly 7l, sincethe perforated pipe is substantially filled with flowing water, most ofthe gas passes through the filter body 99 to filter out smallerparticles carried within the air or gas.

FIG. 14 illustrates anotherl application of a treatment system, whereinthe treatment plant 16 is associated with a relatively largeinstallation such as an industrial factory building or building complex105, wherein there is provided a conventional tall stack 106 to providedraft and to possibly be used in a normal manner under conditions whenthe exhaust air or gases being passed from thel building complex are notso polluted as to require treatment. When the exhaust air or gas passedto the stack 106 does require treatment, the exhaust gas is diverted toa main conduit 107 which opens to the stack at an intermediate height. Ablower 108 draws the air from the main conduit 107 directing it to theinlet section48 and into the inlet conduit 47, or alternatively throughthe bypass conduit 49. A diversion baffle may be provided in the stackabove the main conduit 107 to assist in diverting the gas to thetreatment plant 16. The treatment plant 16 has the same configuration asthat previously described, and the bypass conduit may include the filterassembly 95 as illustrated in FIG. 13.

FIG. is a diagrammatic view of a filtering installation for use in aresidence, for example, including a diagrammatic illustration ofelectric control circuitry. In this installation, a main exhaust conduitor manifold 110 is connected to the exhaust ducts of a barbecue grill111, a fireplace 112 and a range hood 113, to collect from each of theseunits the exhaust air or gases which may tend to pollute the air. Anexhaust fan 114 draws the air from the main conduit l 10, directing itto the inlet section 48 and to the treatment plant 16 as previouslydescribed.

The illustrated control circuit, provides means for actuating thetreatment plant, which would probably be located outside of theresidence structure, through control switches associated with each ofthe household units. As seen in the drawing, power is supplied to theelectric motors for the water pump 52 and the blower 114 throughelectric supply conductors 116 through a main switch 117. Remote controlswitches 118, 120 and 122 are connected in parallel with each other and,as a group, are connected in series with the main switch 117 so that thetreatment plant will be energized when the main switch 117 and any oneof the remote control switches are closed.

The remote control switch l 18 is associated with the barbecue grill111; and the closing of this switch also acts through a solenoid controlto open a shutter 119 in the grill exhaust duct. The remote switch 120is associated with the fireplace 112; and the closing of this switchalso acts through a solenoid control to open a shutter 121 in thefireplace exhaust duct. Similarly the remote control switch 122 isassociated with a range hood 113 and the closing of this switch acts toopen a shutter 123 in the range hood exhaust duct. It will be seen,then, that the closing of any one of the remote control switches 118,120 or 122 will serve to open the exhaust duct shutter for therespective household unit and simultaneously energize the treatmentplant by starting the pump and exhaust fan motors. The shutters for theunits which are not to be used will remain closed so that air will notbe drawn through these units. When it is desired to use two units at thesame time, the closing of the control switch for the second unit willmerely open the respective exhaust duct shutter to connect this unitwith the treatment plant.

OPERATION OF THE PREFERRED EMBODIMENTS The operation of theabove-described systems and apparatus will now be briefly summarized.

Referring to the system and apparatus of FIGS. 1 through 11, pollutedatmospheric air is collected at collection towers 10 appropriatelyspaced in strategic locations where polluted air such as smog maycollect. Each tower includes a suction fan 27 which draws air into thetower inlet and forces the air through a conduit 12, preferablyunderground, to the treatment plant. The towers may includeautomatically controlled shutters 30, responsive to detection ofhumidity or precipitation, to shut off the inlet fans and close thetowers against the entry of precipitation.

At the treatment plant, a blower 14 in the main inlet provides a drivefor forcing the air through the treatment plant 16. The treatment plantincludes an inlet filter assembly 71 and coacting water spray nozzle 79whereby the gas is first contacted with the water spray to wet and flushthe larger solid particles. These are flushed through a centralperforated pipe 72 which is substantially filled with the flowing water,forcing the gas to flow through the annular filter body 76 surroundingthe perforated flow pipe. The water is carried to the bottom of thetreatment tank where heavier particles will settle as sediment to beremoved periodically through a sump system. l

The gas which passes through the inlet filter body is discharged in alower water chamber 67 of the treatment tank then passes upwardlythrough the submerged filter unit 65, through an upper water chamber 66,and is discharged back to the atmosphere through a stack 61. A bypassconduit'49 and discharge conduit system 17 function to bypass thetreatment plant 16 and carry the gas to a remote location in the eventthe treatment plant is inoperative.

In the systems of FIG. l2 through 14, a treatment plant 16 is associatedwith building enclosures for treating the air exhausted from suchbuilding ventilation systems, or polluted gases which may be by-productsof the operations carried on in these enclosures. In these systems thesame type of treatment plant 16 is used. The bypass conduit 49 mayinclude a filter assembly 9S and associated spray nozzle 100, similar tothose of the treatment plant inlet filter, to provide some filtration ofthe air or gas when the treatment plant is inoperative.

FIG. 15 illustrates ra system for use with a residence wherein theexhaust from several household units -is collected and treated, andwherein the system may be energized from any of the individual householdunits without effecting the units which may not be operating.

The method which is employed in the abovedescribed apparatus and systemsfor the treating of polluted air or gas includes the steps of:

l. forcing the gas through a treatment plant;

2. passing the gas through an inlet passageway including an open centralpassage at an annular filter` body;

3. contacting the gas with water spray upstream of the passageway to wetand collect a larger solid particles of the gas; spraying a volume ofwater sut'- ficient to substantially till the central passage therebyeffecting the flow of the gas through the filter body;

4. discharging the gas from the passageway into a water chamber;

5. flowing the gas through water in the chamber and through a submergedmechanical filter, and discharging the cleansed gas to the atmosphere.

While preferred embodiments of the invention have been illustrated anddescribed, it will be understood by those skilled in the art thatchanges and modifications may be resorted to without departing from thespirit and scope of the invention.

What is claimed is:

1. Gas treatment apparatus comprising a water tank; a verticallydisposed inlet conduit for said tank, terminating at its lower endwithin the liquid chamber of the tank;

a filter assembly in said inlet conduit positioned above the water levelof said tank comprising a central perforated pipe and an annularmechanical filter body disposed between said pipe and the conduit walls;

water spray means for discharging into said filter assembly a volume ofwater sufficient to substantially fill the central perforated pipe ofsaid filter assembly.

2. Apparatus as set forth in claim l including separate pipe meanscommunicating the lower end of said filter assembly perforated pipe withthe liquid chamber of said tank to discharge the spray water flowingthrough said perforated pipe at the bottom of said tank;

and pump means associated with said tank, including a suction linecommunicating with said tank adjacent to the bottom thereof, and adischarge line for supplying water to said water spray means.

3. Apparatus as set forth in claim l including a second filter assemblymounted in said tank to be submerged in the water in said liquidchamber; said filter assembly defining a horizontal wall separating saidliquid chamber into upper and lower portions;

said inlet conduit extending through said filter assembly to the lowerliquid chamber, whereby gases emerging from said conduit flow upwardthrough the lower liquid chamber, said submerged filter assembly, andsaid upper liquid chamber.

4. Apparatus as set forth in claim 3 wherein said second filter assemblycomprises spaced parallel perforated plates enclosing a layer of fibrousor granular filtering material.

5. Apparatus as set forth in claim l wherein said water tank is a closedtank; means to maintain the liquid level in said tank to define a gaschamber at the top thereof; and a gas discharge conduit communicatingwith the tank gas chamber.

6. A method for treating exhaust gases to remove irnpurities therefromincluding the steps:

passing the gas through a passageway above and terminating in a body ofwater, said passageway defined by an annular filter body and a centralperforated open passage;

contacting the gas at the upstream end of said passageway with a volumeof spray water sufficient to substantially fill said central passagewhereby the gas is caused to pass through the filter body;

and flowing the gas emerging from said passageway through said body ofwater.

7. A method as set forth in claim 6 including the step:

Y passing said gas through a mechanical filter unit submerged in saidbody of water.

2. Apparatus as set forth in claim 1 including separate pipe meanscommunicating the lower end of said filter assembly perforated pipe withthe liquid chamber of said tank to discharge the spray water flowingthrough said perforated pipe at the bottom of said tank; and pump meansassociated with said tank, including a suction line communicating withsaid tank adjacent to the bottom thereof, and a discharge line forsupplying water to said water spray means.
 3. Apparatus as set forth inclaim 1 including a second filter assembly mounted in said tank to besubmerged in the water in said liquid chamber; said filter assemblydefining a horizontal wall separating said liquid chamber into upper andlower portions; said inlet conduit extending through said filterassembly to the lower liquid chamber, whereby gases emerging from saidconduit flow upward through the lower liquid chamber, said submergedfilter assembly, and said upper liquid chamber.
 4. Apparatus as setforth in claim 3 wherein said second filter assembly comprises spacedparallel perforated plates enclosing a layer of fibrous or granularfiltering material.
 5. Apparatus as set forth in claim 1 wherein saidwater tank is a closed tank; means to maintain the liquid level in saidtank to define a gas chamber at the top thereof; and a gas dischargeconduit communicating with the tank gas chamber.
 6. A method fortreating exhaust gases to remove impurities therefrom including thesteps: passing the gas through a passageway above and terminating in abody of water, said passageway defined by an annular filter body and acentral perforated open passage; contacting the gas at the upstream endof said passageway with a volume of spray water sufficient tosubstantially fill said central passage whereby the gas is caused topass through the filter body; and flowing the gas emerging from saidpassageway through said body of water.
 7. A method as set forth in claim6 including the step: passing said gas through a mechanical filter unitsubmerged in said body of water.